An ultrasound coupling agent, otherwise known as a “gel”, is designed to act as a conductive barrier between an ultrasound probe and the outer layer of skin, known as the epidermis. A gel providing excellent acoustics is a necessity in order to produce the appropriate reflection of sound waves useful to a valid diagnosis.
In order to properly transmit ultrasonic impulses, the gel must be a medium that can uniformly produce uninterrupted quantitative parameters for measurement of acoustic velocity, impedance, and attenuation. These parameters are all necessary to yield a competent diagnosis via ultrasound technology.
Ultrasound diagnostic procedures are used in assessing and diagnosing a wide variety of medical conditions related to internal organs. Perhaps the condition most familiar to the general public is with regard to development of a fetus during pregnancy. Ultrasonography uses ultrasound scanning to produce images on a cathode ray tube or television screen. It is widely used in obstetrics for several purposes, including confirming pregnancy under circumstances where hormonal tests cannot be used, for establishing gestational age and the number of fetuses, for determining sex of the fetus, for detecting fetal abnormalities or fetal death, for monitoring fetal growth, as an adjunct to amniocentesis, etc. Ultrasound Doppler scanning may also be used to test fetal blood flow. Ultrasonography is a valuable technique, since it provides a safe alternative to roentographic or X-ray techniques.
The procedure typically will involve the application of a gel to the patient's abdomen. A piezoelectric transducer that generates sound waves at a frequency in the range of 2.25 to 7.0 MHz is placed in the gel and moved across the abdomen to form images at different angles. The sound waves reflect off tissues to produce an echo signal that can be converted to images that can be viewed on a screen and interpreted by a competent medical practitioner. The gel lubricates the abdomen and prevents the sound waves from being trapped or reflected by air pockets that might distort the image and lead to an incorrect diagnosis. Typically, after completion of the ultrasound examination, any remaining gel is wiped off the patient's abdomen. For instance, U.S. Pat. No. 8,133,516 discloses lubricants used for medicinal purposes and to skin care compositions, and particularly to a therapeutic ultrasound gel used as a lubricant during ultrasonography procedures that enhances the transmission of sound waves and that also helps to prevent the formation of stretch marks.
While several gels are available, there is still a need for a gel that can enhance the transmission of sound waves from the transducer into the abdominal cavity while at the same time containing ingredients that are medically safe and non-toxic.
Coupling agents have never fit into the “environmentally friendly and sustainable” category because of the chemical formulation(s) typically used in manufacturing. The known commercially available coupling agents have high concentrations of known irritants like propylene glycol or suspected estrogen mimics such as parabens. These molecules are synthetically derived from other than renewable materials.
Increasingly, manufacturers of personal care products are responding to customer interest in more environmentally friendly and sustainably sourced products. Regulatory schemes including those of federal and state governments increasingly reflect these concerns, as well.
Propylene glycol is a known general purpose coupling agent that is often used in ambient temperature in thickness gauging applications on smooth surfaces. Glycerin is also another known general purpose coupling agent, but it is more viscous and has higher acoustic impedance than propylene glycol. This property makes it a preferred coupling agent for rough surfaces and highly attenuating materials. However, these and other known ultrasound coupling agents typically have high concentrations of known irritants and/or estrogen mimics. In fact, many of these known coupling agents include one or more toxic components known to be toxic under California Proposition 65 (1986) (see http://oehha.ca.gov/proposition-65/proposition-65-list).
The United States Department of Agriculture (USDA) set forth organic regulations in the Federal Code of Regulations (CFR) in Title 7, subtitle 205. Accordingly, a nontoxic component is a component not known to cause any adverse physiological effects in animals, plants, humans, or the environment. Under § 205.200—General—the producer or handler of a production or handling operation intending to sell, label, or represent agricultural products as “100 percent organic,” “organic,” or “made with organic (specified ingredients or food group(s))” must comply with the applicable provisions of this subpart. As a result, production practices implemented in accordance with that section must maintain or improve the natural resources of the operation, including soil and water quality.
Thus, it is desirable to obtain a coupling agent having one or more non-toxic components that are environmentally friendly and sustainable and derived from a natural resource that utilizes the resource, it constituent parts, and its by-products in a variety of uses and in a manner that reduces waste.